Win2k Rig, wanting best performance

What I have is a Dell Dimension 8300 Series desktop PC that originally ran WinXP, but I've taken the best parts for it that I had on hand, slapped them inside, and loaded Win2k. Reason? Old games of course.

What I want to know is: What kind of badass hardware can I put in here that is compatible with Win2k? I have searched a bit online about what kind of graphics might work, but the only piece of info I've found so far is what the nVidia drivers for Win2k supported (I believe it was up to GeForce 8 series). But what's the best card that Win2k supports? Also, what kind of CPU can I upgrade this to?

I don't want to know an easier way to get top performance for older games (I'm pretty sure there is one), so please don't call me out on taking a pointless project. I want to know what Windows 2000 can actually do on legit hardware.